The U.S. has some of the world's busiest airports: In fact, 12 of the world's top 30 were in the U.S. in 2012. But busy airports aren't necessarily good ones, and big doesn't mean user-friendly. (None of the top-10 U.S. airports earned an Airline Service Quality award from Airports Council International.) Still, you'll probably have to cope with at least one of these monsters—and sometimes two—on an upcoming trip. So knowing helps.

This report is written from the standpoint of a visitor unfamiliar with each airport and does not include some of the special gimmicks regular travelers or residents might use. The most widely used airport-traffic data measure the sum of deplaned, enplaned, and direct-transfer passengers, and the numbers for each major airline include passengers flown by affiliated regional carriers.